Some groups allow you to look around first. If you then want to join, you can click on the 'Join Now' button which is on the navigation bar on the left of the page.
Other groups are private which means you have to join to be able to see the content. If you try to access the group, you will get the following screen:
Whether you click on the Join Now button within the group or the Apply To Join button on the above screen, the process that follows is the same.
After you have clicked, this is the screen you will see, with an explanation of what each part is:
When you have completed your application and clicked on Join Now, the only thing you need to do is keep an eye on your inbox. When your application is either accepted or rejected by the Group, an email will be sent to you notifying you. Once you have been accepted, you can then access the group - either by typing in the address, if you know it, or clicking on the link that will be in the acceptance email.
You may need to be patient - some groups check for applications regularly, others only check once a day, so don't worry if you do not get a fast response!
After Joining a group, or becoming accepted into a group by the manager, go to Member tools, then Check Your E-mail Settings. Decide how and when you receive e-mail. Change your e-mail address and visibility. It is always good to re-check your email visibility, along with concluding with the last two options upon joining a group.
Some members do prefer to get weekly reports, one reason being they can easily find the groups they have just joined if they have not bookmarked them. Also the difference in email preference is text uses less space in email inbox than html format.